This invention relates to apparatus and methods for digging trenches in the earth's surface for laying pipes and the like, and more particularly to apparatus and methods for cutting narrow vertical walled trenches in solid rock such as limestone.
References which are known to the present applicant and which are believed to be relevant to the present invention include the following U.S. Pat. Nos. 1,472,563 issued to Loken on Oct. 30, 1923; 2,780,452 issued to Marcerou on FEB. 5, 1957; and 3,364,602 issued to Renzaglia on Jan. 23, 1968.
The Loken patent discloses improvements to the bucket wheel trenching machines commonly used for pipe laying. Such machines are quite useful in most normal soils and even in some soft rocks, but the depth of cut is limited by the diameter of the bucket wheel itself. For very large depths, the equipment becomes quite massive.
The Marcerou patent teaches a rock cutting machine for use in quarries. The machine is manually adjustable and is designed to drive a pair of relatively small rock cutter wheels into the face of a stone wall while a head tool cuts a hole for the driving equipment and a pair of side cutters cut side grooves for stabilizing the device as it penetrates into the rock.
The Renzaglia patent teaches the use of a larger cutter wheel pivotally mounted on the back of a tractor for use in cutting roots. It is apparent from the illustrated apparatus that the depth of cut provided by this apparatus is limited to somewhat less than the radius of the cutter wheel.
Thus it is seen that while rock saws or cutter wheels have been known and used for various purposes, they have not been applied to the cutting of trenches for laying of pipelines. It can also be seen that it is desirable to provide a trench cutting apparatus capable of digging deep, narrow trenches in hard rocky materials which is relatively lightweight and simple compared to the prior known devices.